If you want to watch the best version of Dragon Ball, you need to watch:
1. Dragon Ball
2. Dragon Ball Z
3. Dragon Ball Super
Kai is a lazy, shitty, low budget, cash grab, edited down version of DBZ done 20 years after the fact. It's not fucking good. It's shorter than the original version, of course, but it's fucking weird and the animation is all over the god damn place because there's like 3 episodes of Z being spliced into 1 episode of Kai.
I highly recommend watching the original Japanese version of Dragon Ball and Z. It's a lot of episodes, but it's WELL worth it. We aren't just talking about any cartoon here. This is one of the most influential and popular pieces of animation in the history of the world, and for good reason.